The proposed research will be a study of the mechanisms involved in the enzymatic biosynthesis of polysaccharides found in dental plaque, viz., dextran, mutan, and levan. This will entail: 1. the purification of the enzymes responsible for the various biosyntheses, i.e., the polysaccharide sucrases; 2. the coupling of these enzymes to a bead-solid support to produce a model bacterial-enzyme system to study the polysaccharide biosyntheses; 3. the synthesis of a sucrose substrate analogue, xylsucrose, which has the potential for terminating dextran biosynthesis by forming dead-end complexes; 4. the testing of an hypothesis relating to polysaccharide acceptors being involved in the formation of branch points; 5. the testing of the possibility of forming graft polysaccharides by adding levan, mutan, and amylodextrin as acceptors to a dextran-dextransucrase system; and 6. the subjection of these polysaccharides to structural analyses using scanning electron microscopy, fourier transform C13-NMR, and enzymatic degradation using dextranases, mutanase and glucoamylase.